Inasmuch as the lack of variety, the monotonous prior wheel rim frame of bicycle has failed to exhibit personal characteristics to attract prospective consumers, hence, some kinds of sticker designed with various stripes or warning patterns have been proposed showing its specialties or security purposes. However, owing to the poor weather durability, the stickers are liable to be disintegrated or detached after some period of weather inclemency. Subsequently, spray painting follows the sticker to be another option with inherent imperfections, such as only simple pattern available, longer working time required, higher cost spent, or being scraped easily, and in the long run, the sticker becomes unrecognizable. The lately developed wheel rim protective envelope in the same shape with the wheel rim frame and being printed with stripes is mounted on the wheel rim frame and rolled together to form a circle and finally a wheel rim. In this case, due to many a lot of wheel rim frame of various cross sections in the market, it seems rather thorny for producing different type protective envelopes to match all kinds of wheel rim frame with high manufacturing cost and procession difficulties. Moreover, a protective envelope shall inevitably increase the weight of a wheel rim frame, and it may consequently affect operation of a bicycle in case of imbalance. In view of the above-described defects, the inventor is to propose an improved structure concerning the subject article for another choice.